Full Stack Developer 路 Intern to senior
Full stack interviews sample both sides: a question about React state, then one about SQL indexes or API design. Interviewers look for breadth plus a few areas where you go deep.
158 questions
ACID stands for Atomicity, Consistency, Isolation and Durability: a transaction either fully succeeds or fully fails, keeps the data valid, does not interfere with other transactions, and survives crashes once committed.
An index is a separate sorted data structure (usually a B-tree) that lets the database find rows without scanning the whole table, at the cost of extra storage and slower writes.
A clustered index defines the physical order in which the table's rows are stored, so there can be only one per table, while a non-clustered index is a separate structure that points back to the rows.
IEnumerable runs the query in memory using delegates, while IQueryable builds an expression tree that a provider such as Entity Framework translates into SQL, so filtering happens in the database.
Transient services are created every time they are requested, scoped services are created once per HTTP request, and singleton services are created once and shared for the life of the application.
A Thread is an operating-system execution unit, while a Task represents an asynchronous operation scheduled on the thread pool; await releases the current thread while the operation is pending and resumes the method when it completes.
The .NET garbage collector automatically frees managed objects that are no longer reachable, organising them into generations 0, 1 and 2 so short-lived objects are collected cheaply, and IDisposable is used to release unmanaged resources such as files and connections promptly.
A HashMap stores entries in an array of buckets; it computes the key's hash code to choose a bucket, resolves collisions with a linked list that becomes a red-black tree when a bucket grows large, and resizes when the load factor of 0.75 is exceeded.
Choose SQL when your data is relational and you need transactions, joins and strong consistency; choose NoSQL when you need flexible schemas, very high write throughput or horizontal scaling for a specific access pattern.
Caching stores frequently read data in fast storage such as memory to reduce latency and database load; the main strategies are cache-aside, write-through, write-back and time-based expiry (TTL).
REST exposes resources over HTTP URLs and is simple and cache-friendly, GraphQL lets clients ask for exactly the fields they need from a single endpoint, and gRPC uses binary Protocol Buffers over HTTP/2 for fast service-to-service calls.
An operation is idempotent if repeating it any number of times has the same effect as doing it once; it matters because network retries can otherwise create duplicate orders or payments.
Choose an algorithm such as token bucket or sliding window, store a counter per client (by user ID, API key or IP) in a fast shared store like Redis, and return HTTP 429 with a Retry-After header when the limit is exceeded.
git revert creates a new commit that undoes an earlier one and is safe on shared branches; git reset moves the branch pointer back to an earlier commit, effectively removing later commits from that branch鈥檚 history.
Docker Compose defines a multi-container application (services, networks and volumes) in one YAML file so you can start, stop and rebuild the whole stack with a single command, typically for local development and testing.
Treat a flaky test as a bug: quarantine it so it stops blocking the pipeline, reproduce it by running it repeatedly, fix the root cause (usually timing, shared state or external dependencies), then bring it back.
Selenium is the long-established, language-agnostic standard built on WebDriver; Cypress runs inside the browser with an excellent developer experience for JavaScript apps; Playwright offers fast, auto-waiting cross-browser automation with multiple tabs, contexts and languages. For a new web project, Playwright is usually the strongest default.
Describe a real technical or process disagreement, show that you listened and argued with evidence rather than opinion, explain how a decision was reached, and how you supported it afterwards even if it was not your idea.
Describe a problem you noticed, why you decided to act, how you coordinated with others, and the impact of taking ownership.
Explain how you identified ambiguity, clarified the important decisions, made reasonable assumptions and kept delivery moving.